Garment and fabric processing today includes dyeing and desizing. Sizing is important in the fabric weaving process. The size is usually removed in a finishing operation after the fabric is woven. In some fabrics e.g. denim, the size is left in to give desirable properties to the denim garment so as to improve the wear properties of the fabrics or garments. However, if the garments or fabrics are further processed, for example, treated with a crosslinking agent and/or decolorized or finished in garment form, it is necessary to first remove the sizing.
The removal of sizing is today performed in most textile plants by one or more of the following methods. The primary method of desizing is enzymatically, for example utilizing amylolytic enzymes. In garment finishing, this process is more costly. Mechanical action is another method of desizing. In this method, abrasive drum linings in extractors and/or pumice stones are utilized to improve the garment softness, give the garment special features, etc. Alkaline and acidic hydrolysis have also been employed but such techniques also cause chemical attack of the fabric so as to result in a loss of the abrasive strength of the fabric. Oxidative desizing is generally employed using large amounts of sodium hypochlorite in solution. The use of hypochlorite creates environmental problem and further can significantly degrade the fabric. Desizing is required where the fabrics or garments are to undergo further processing such as dyeing, printing, decolorization, treatment with a crosslinker, bleaching treatments and the like.
Stone washing is a technique used in the denim industry to decolorize and soften denims, especially denim garments. In practice, abrasive stones are placed with the garments or fabrics in a washer-extractor which is rotated. The stones pound the fabrics or garments and causes softening of the garment or fabric The stones further break off sizing and remove some of the dye. The stones have the disadvantage in that they are difficult to remove and also must be continuously replaced.